1. Field of the Invention
The invention is directed to a lateral register system, in particular for flexible printing forms which are held by their edges in axially extending gaps in a plate cylinder, these edges being pre-bent according to the inclination of these gaps.
2. Description of the Prior Art
At least one gap which is inclined at a determined angle is provided in the plate cylinder in order to fasten flexible printing forms. The ends of the printing forms which are bent in a defined manner are inserted into this gap. A plate cylinder with an axially extending gap whose opening is inclined in the rotating direction of the plate cylinder and which receives the two ends of the printing form, i.e. the bent edges, is from DD 226 251, for example. If two or more printing forms are fastened in the plate cylinder in its circumferential direction, two or more gaps which are offset by 180.degree. relative to one another must be provided in the circumferential direction. In so doing, the ends of the printing form are shaped so that they are held in the slots even at high printing speeds. To improve reliability of operation, the edge of the printing form inserted in the gap after the preceding edge has an additional edge which is designed so that the subsequently inserted edge is resiliently supported against the preceding edge in the gap.
A simple lateral register system is possible in the gap of the plate cylinder. The gap is penetrated vertically with respect to its lateral surfaces by positioning pins which are pressed into corresponding bore holes of the plate cylinder so as to terminate flush with the plate cylinder circumferentially. Of course, such a register system does not provide the possibility for lateral displacement of the printing forms on the plate cylinder.
However, a problem in rotary printing presses with a plurality of printing mechanisms arranged one after the other is that the paper webs to be printed vary in width during printing due to their quality and absorption of the moistening medium. This change in width can differ from one printing mechanism to another.
The register pins for two printing forms which are arranged adjacent to one another on a plate cylinder can be displaced axially by means of a lateral register system, as is already known from the European Patent EP 0 229 892 B1. For this purpose, the register pins are connected with a common adjusting screw by means of an adjusting rod or an adjusting tube via threads of different pitches. In this way, the register pins for two adjacently arranged printing forms can always only be adjusted at the same time and with a fixed gear ratio. It is not possible to adjust the individual register pins, and accordingly the individual printing forms, separately so as to take into account the changing paper parameters.